Blasting Prostate Cancer Cells with Precisely Controlled Chemotherapy

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Researchers at Johns Hopkins say they have developed a method for finding and killing malignant cells while sparing healthy ones. Experimenting with human prostate cancer cells and mice, they used a method called theranostic imaging to target and track potent drug therapies directly and only to cancer cells.

Theranostic imaging relies on binding an originally inactive form of drug chemotherapy, along with an enzyme, to specific proteins on tumor cell surfaces and detecting the drug’s absorption into the tumor. The binding of the highly specific drug-protein complex, or nanoplex, to the cell surface allows it to get inside the cancerous cell, where the enzyme slowly activates the tumor-killing drug.

Researchers say their findings are believed to be the first to show that chemotherapies can be precisely controlled at the molecular level to maximize their effectiveness against tumors, while also minimizing their side effects.

“Our results show a noninvasive imaging approach to following and delivering targeted therapy to any cancer that expresses PSMA,” says senior study investigator Zaver Bhujwalla, Ph.D., a professor at the Johns Hopkins University School of Medicine and its Kimmel Cancer Center, who also serves as director of the Johns Hopkins In Vivo Cellular and Molecular Imaging Center, where the theranostic imaging studies were developed.

Dr. Bhujwalla says the new technique potentially will work against any cancer in which tumors elevate production of certain cell surface proteins. Examples would include breast cancers with HER-2/neu and CXCR4 proteins, and some liver, lung, and kidney cancers also known to express particular proteins. She notes that PSMA is expressed in the vessels of most solid tumors, suggesting that the nanoplex reported in the latest study could be used in general to image and treat a variety of cancers.

The study appears in the journal American Chemical Society Nano, published online August 6. The paper is titled “A PSMA-targeted Theranostic Nanoplex For Prostate Cancer Therapy”.